main {
    width: 300px;
    padding: 52px 29px;
    display: flex;
    justify-content: center;
    border: solid 1px #fff;
    
  }
    div {
      background-color: #f6e58d;
      width: 200px;
      height: 200px;
    }

  .wave-border {
    border: 10px solid transparent;
    padding: 15px;
    /* border-image: url('https://www.runoob.com/images/border.png') 30 round; */
    border-image: url('https://www.runoob.com/images/border.png') 30 round;


  }